This invention relates to mixed gas storage and delivery apparatus and methods, and, more particularly, relates to integrated systems for storage, delivery and conditioning of mixed gas initially contained at cryogenic temperature.
High pressure, ambient temperature gas storage and delivery devices have been heretofore suggested for providing attitude independent supply of mixed gasses such as breathable air to a user thereof. Such devices, while in use, have limited gas delivery time, are bulky, and must be operated at extremely high pressures.
Liquid air storage and delivery devices have also been suggested (see U.S. Pat. Nos. 1,448,590, 3,318,307, 3,570,481, 3,572,048, 4,181,126, 3,699,775, 1,459,158, and 3,227,208), but suffer from limited stand-by time due to oxygen enrichment inherent in such storage, some being unduly complex in an effort to confront this problem, are not attitude independent, and are often quite heavy.
Dispensers for cryogenic temperature elemental and compound gasses (below xe2x88x92175xc2x0 F.) such as oxygen held for use at supercritical pressure (above 730 psia) have been heretofore suggested (see U.S. Pat. Nos. 3,062,017 and 3,827,246) In such dispensers a heat transfer mechanism (i.e., an electrical heating element or a heat exchanger) is utilized to pressurize the storage vessel having liquid oxygen loaded therein at atmospheric pressure (thus making the dispenser less than desirable as an air supply, where oxygen enrichment could occur while liquid air is in standby storage) for expelling the oxygen.
Pressure sensing is thereafter used to sense the heat transfer needs in the vessel to maintain pressure therein above critical pressure by activating the heating element periodically. Heat exchange is accomplished utilizing at least in part active means separate from the dewar thus encumbering these heretofore known dispensers with complex sensing and activating mechanisms to assure proper heat input. Improvement in such dispensers could thus still be utilized.
While the integrated system above described may be effective in some applications, such system fails to provided a compact unit (capable of being carried on one""s body) such as might be required by fire fighters or other mobile personnel needing such a system. Such systems require electrical input (undesirable in gaseous environments), rely on manual activation to control flow rates and thus cooling, and make no use of heat exchange to control system operational parameters other than temperature of the breathable air. Moreover, the oxygen converting systems used therein suffer many of the same drawbacks as heretofore discussed. Further improvement could thus be utilized.
This invention provides a body mountable mixed gas storage and delivery system and method which maintains conditioning of a mixed gas for end use. The system is lightweight and includes a containment apparatus (or vessel) for storing mixed gas received at cryogenic temperature and supercritical pressure and delivering the mixed gas at a non-cryogenic temperature to a utilization fixture, such as a breathing mask in the case of air or a torch or engine in the-case of other mixed gasses. The system requires no electrical input, requires no manual manipulation to control cooling fluid flow rates, and makes use of passive heat exchange for control of system operational parameters including temperature of the usable gas and maintenance of remaining stored gas in a single phase and at,proper expulsion pressure.
The containment vessel has an outlet for selective expulsion of the mixed gas from the containment vessel to the utilization fixture and a passive heat exchanger thereat for receiving mixed gas expelled through the outlet and routing the mixed gas at the containment vessel to introduce sufficient heat into the containment vessel so that the mixed gas remaining in the containment vessel is in a single phase. Heat exchange is calculated and configured for introducing heat into the containment vessel at a rate determined by the rate of expulsion of the mixed gas from the containment vessel through the outlet to thereby maintain sufficient energy to expel the mixed gas remaining in the containment vessel and so that the mixed gas remaining is in the single phase.
A body mountable unit is provided and includes a pack structure configured for releasably receiving the containment vessel. The unit includes conditioning means integrally maintained in the pack structure and connectable with the passive heat exchanger when the containment vessel is mounted in the pack structure, the conditioning means for raising the temperature of the mixed gas to a usable temperature.
The containment vessel preferably includes a pressure vessel having an inlet and outlet and an outer shell having the pressure vessel therein. Surface area increasing means, such as fins, are connected with the outer shell for effectively increasing surface area of the outer shell, the mass flow heat exchanger connected adjacent to the outer shell and with the outlet of the pressure vessel for receiving the mixed gas from the pressure vessel through the outlet and conducting it to a connection.
The body mountable unit preferably includes a quick disconnect connected with the conditioning means and readily connectable/disconnectable with the connection of the heat exchanger when the containment vessel is mounted in the pack structure.
The method for storing and delivering mixed gas of this invention includes the steps of loading cryogenic temperature mixed gas into a container so that the mixed gas at time of use is in a single phase, with the container configured to be mountable in a pack that can be carried on the body of a user. Mixed gas is selectively expelled from the container and routed to deliver sufficient heat to the container so that mixed gas remaining in the container remains in the single phase. The expelled mixed gas is received, conditioned for end use, and delivered at structure integrally associated with the pack.
It is therefore an object of this invention to provide an improved self contained cryogenic mixed gas single phase storage and delivery system and method.
It is another object of this invention to provide an improved integrated body mountable mixed gas storage, conditioning and delivery system and method.
It is still another object of this invention to provide a lightweight apparatus for storing mixed gas received at cryogenic temperature and supercritical pressure and delivering the mixed gas at a non-cryogenic temperature to a utilization fixture, such as a breathing mask in the case of air or a torch or engine in the case of other mixed gasses.
It is still another object of this invention to provide a cryogenic mixed gas storage and delivery apparatus which makes use of heat exchange for control of apparatus operational parameters including temperature of the usable gas and maintenance of remaining stored gas in a single phase and-at proper expulsion pressure.
It is another object of this invention to provide a body mountable system for mixed gas storage and delivery comprising containment means for receiving mixed gas at cryogenic temperature and in an amount so that the mixed gas is initially at a pressure sufficient to maintain the mixed gas in a single phase, outlet means connected with the containment means for selective expulsion of the mixed gas from the containment means therethrough, passive heat exchange means connected with the outlet means for receiving the expelled mixed gas at the outlet means and conducting the expelled mixed gas to a connection, the heat exchange means being routed for introducing heat into the containment means at a rate determined by a rate of expulsion of the mixed gas from the containment means through the outlet means to thereby maintain sufficient energy to expel the mixed gas remaining in the containment means from the containment means and so that the mixed gas remaining in the containment means remains in the single phase.
Is is another object to provide a body mountable unit including a pack structure configured for releasably receiving a cryogenic fluid container and passive heat exchange means therein, the unit including conditioning means integrally maintained in the pack structure and connectable with the connection of the passive heat exchange means when the containment means.
It is another object of this invention to provide an air storage and delivery system comprising an air storage and maintenance unit including a pressure vessel for containing air at cryogenic temperature and at a pressure so that air in the vessel is in a single phase, the vessel having an inlet and an outlet, an outer shell having the pressure vessel therein, and mass flow heat exchange means connected adjacent to the outer shell and with the outlet of the pressure vessel for receiving the air from the pressure vessel through the outlet and conducting the air to a connection, the heat exchange means being routed for introducing heat by free convection into the air being conducted to the connection and into the pressure vessel from the air thus routed to thereby maintain sufficient energy in the pressure vessel to expel the air therefrom.
It is still another object of this invention to provide a method for storing and delivering mixed gas comprising the steps of loading cryogenic temperature mixed gas from a source at or above supercritical pressure into a container so that substantially immediately after time of loading the mixed gas is at or above supercritical pressure in the container and at time of use is in a single phase, selectively expelling the mixed gas from the container, and routing the expelled mixed gas to introduce heat into the container during conduct or the mixed gas toga destination for use, heat introduction sufficient to maintain the mixed gas remaining in the container in a single phase and with sufficient continued expulsion energy based subastantially solely on rate of expulsion of the mixed gas from the container.
With these and other objects in view, which will become apparent to one skilled in the art as the description proceeds, this invention resides in the novel construction, combination, arrangement of parts and method substantially as hereinafter described, and more particularly defined by the appended claims, it being understood that changes in the precise embodiment of the herein disclosed invention are meant to be included as come within the scope of the claims.